Those long sunny days are coming to an end, which means the days are shorter and the nights are cooler… your window for finishing up your outdoor painting projects is also closing. With weather like this, it is important to beware of exterior painting when those temperatures drop. Painting when the weather is too cold is a mistake that will leave you with unsightly consequences, and will lessen the life of the paint.

Premature failure due to the film freezing. If the film is unable to coalesce correctly, the paint, at a microscopic level will look like alligator skin.

The paint will not bond to a substrate that is is frozen or below surface temp recommendation. This includes the 24 to 48 hours after application depending upon Manufacturer Specifications.

In the morning, if the surface is not adequately dry or up to manufacturer’s recommended temperature you could potentially be sealing in moisture that will find its way to the surface. Depending upon the amount of moisture migrating through the film, it could pop the paint off the surface and be filled with water. It will look like your surface has water blisters. Sometimes, if you pop the “water blisters” they will shrink back down; however, you have a pin hole in your film that will let water in over time. The damage will have been done to have premature coatings failure.

Most manufacturers instruct homeowners to apply latex paints when ambient and surface temperatures are at least 50 degrees. Below 50 degrees, latex paints dry more slowly, especially when high humidity is present. This hinders coalescence, which can lead to poor film-forming, lack of surface adhesion and premature paint failure.

Some manufacturers offer latex paints that can be applied at temperatures as low as 36 degrees F. These specially formulated products contain coalescing agents that aid in film-forming during lower temperatures. When a manufacturer says Latex can be applied as low as 36 degrees F, the ambient temperature and/or surface temperature needs to stay above that for 24 hours for proper film forming rk MILES does stock an exterior latex paint line and an exterior solid color latex stain line that is rated to 36 degrees. They are both manufactured by California Paints.

Daylight plays a big role in the paint drying process. When the days are short, there is less daylight available to aid in drying. So, be sure to paint early in the day so that light is present to add in the drying process.

Humidity affects the drying time of all paints, but especially latex paints so you must also consider the effects of heavy dew. Most manufacturers recommend that at least two hours be allowed for paint to dry before sunset if cool temperatures and heavy dew are expected that evening. Remember to give some time in the morning for any heavy dew to dissipate off the surface.

Finally, keep in mind that cooler temperatures may extend the time before the paint reaches serviceability or hardness. An enameled door requires more time before it can be closed without sticking to the jamb. A clear coating applied to a deck will need more time before you can walk on it. Primers require more time before top-coating. Knowing all of this may aid you as you go about your painting chores this Fall.